The present invention relates generally to radio frequency identification (RFID) systems, and more specifically to a system and method of managing the configuration and control of components of an RFID system, taking into account how the RFID system components are associated with one or more physical locations within an environment in which the RFID system is deployed.
In recent years, radio frequency identification (RFID) systems have been employed in an ever increasing range of applications. For example, RFID systems have been employed in supply chain management applications to identify and track merchandise throughout manufacture, warehouse storage, transportation, distribution, and retail sale. RFID systems have also been used in security applications to identify and track personnel for controlling access to restricted areas of buildings and plant facilities, thereby prohibiting access to such areas by individuals without the required authorization. Accordingly, RFID systems have been employed in a number of diverse applications to facilitate the identification and tracking of merchandise, personnel, and other items and/or individuals that need to be reliably monitored and/or controlled within a particular environment.
A conventional RFID system typically comprises at least one RFID reader including at least one RF interrogator and at least one RF receiver, at least one controller or host computer, and at least one RFID transponder or tag. For example, when such a system is deployed in a manufacturing environment, one or more RFID tags may be attached to selected items of manufacture or equipment, and one or more RFID readers may be employed to interrogate the RFID tags as the tagged items pass predefined points on the manufacturing floor. Each of the RFID tags may include a memory for storing information provided to it by one of the RF interrogators. In addition, one or more of the RFID tags may include an integrated transducer or environmental sensor, which may be employed to acquire data relating to the temperature, pressure, and/or humidity level of the ambient environment. RFID tags generally belong to one of the following class categories: identity tags for holding user data (class 1), secure tags (class 2), battery assisted tags containing real time sensors (class 3), and fully battery-operated transceiver-based tags providing interactivity with other similar tags within the RFID system. Because they do not contain a power source, RFID tags belonging to classes 1-2 are called passive tags. Such passive tags typically receive energizing power from an impinging RF field generated by an RF interrogator.
In a typical mode of operation within an exemplary manufacturing environment, the RF interrogator transmits an RF signal in the direction of an RFID tag, which responds to the transmitted signal by generating another RF signal containing information stored on the tag. For example, such information may identify the item to which the RFID tag is attached, and may possibly contain other data acquired during the manufacture of the item. As described above, if the RFID tag includes an environmental sensor, then the tag may also provide data relating to the temperature, pressure, humidity level, etc., of the ambient environment. The RF receiver receives the RF data signal transmitted by the RFID tag, and provides the tag data to the controller or host computer for subsequent processing and decision making based upon the data. In this typical operating mode, the RFID reader can be configured as a peripheral connected to a serial port of the controller or host computer.
More recently, RFID readers have been developed that are capable of being connected via one or more communications networks to enterprise computer resources running one or more RFID-enabled client software applications. Such RFID readers have been employed in complex systems including a multiplicity of readers connected via a number of communications networks to one or more host computers, which may be part of an enterprise network server. For example, such host computers may be configured to run client applications for processing tag data to control access to building and plant facilities, to control the movement of personnel and/or property within a predefined area, to control the operation of lighting, heating, ventilation, and/or air conditioning facilities, and to perform numerous other diverse functions. In addition, networks of RFID readers and other RFID system components can be operated as distributed sensor networks configured to acquire information from multiple points within the system environment, and to combine the acquired information for use in subsequent decision making to achieve a specified business purpose.
Whether implemented as computer peripherals or networked devices, conventional RFID readers generally collect data from RFID tags like optical barcode readers collect data from barcode labels. However, whereas an optical barcode reader typically requires a direct line of sight to a barcode label to read the data imprinted on the label, the RF signals generated by the typical RFID reader can penetrate through and/or diffract around objects obstructing an RFID tag from the RF field of view of the reader, thereby allowing the reader to access data from a tag that, for example, might be buried beneath one or more boxes of material. In addition, the conventional RFID reader can typically operate on and distinguish between multiple RFID tags within the reader's field of view.
However, conventional RFID systems like those described above have drawbacks. For example, when a conventional RFID system including multiple RFID readers is configured to operate within a distributed sensor network, two of the RFID readers may be disposed at points that are far enough apart so that the RF fields generated by the respective readers do not cover the same physical space. Within such a distributed sensor network, a tagged item carried by a conveyor belt or a vehicle may first pass through the RF field of view of one of the RFID readers, and then pass through the RF field of view of the other reader. Based upon the locations of the respective readers within the system environment, and the times when the RFID readers detect the tagged item passing through their respective fields of view, the RFID system can determine the direction of travel of the tagged item.
The operation of such a conventional RFID system can be problematic, however, because various factors such as multi-path propagation, RFID tag orientation, shadowing by an obstruction, etc., may prohibit the two RFID readers from successfully interrogating the tagged item at particular angles of interrogation. For example, if the RFID readers are placed too close together within the system environment, then the order in which the readers detect the tagged item within their respective fields of view may vary, thereby making it difficult to determine reliably the direction of travel of the tagged item. Further, one of the RFID readers may fail to detect the tagged item altogether, thereby making it virtually impossible to determine the item's direction of travel. Moreover, interference between the two RFID readers may prohibit the readers from successfully interrogating the tagged item. Such reader-to-reader interference may also prevent the two RFID readers from occupying the same frequency channel in the same time slot within a particular RF domain, resulting in significant degradation in the efficiency of the distributed sensor network.
In addition, conventional RFID systems are often configured such that the various system components, for example, the RF interrogators, the RF receivers, and/or the RFID readers, are provided with designations without maintaining any meaningful associations between the system components and actual physical locations within the system environment. For example, RF interrogators, RF receivers, and/or RFID readers may be provided with names indicating their intended placement and function (e.g., shipping or receiving) within the system environment. However, in conventional RFID system configurations, there is no easy way of tying the named system components to the physical locations corresponding to those functions indicated by the named designations. For example, if one of the named system components is moved from one physical location to another physical location within the system environment, then the name of that system component typically moves with the component, causing the component to remain within the same functional grouping (i.e., shipping or receiving) in which it was originally configured. Conventional RFID system configurations are generally incapable of incorporating any formal understanding of how groups of system components relate to the physical space in which they are employed.
Further complications can result if a system component (e.g., an RF interrogator, an RF receiver, and/or an RFID reader) can be used to perform more than one function. For example, there may be an overlap of the interrogation zones corresponding to two groups of RFID system components configured to perform shipping and receiving functions, respectively. However, conventional RFID systems typically provide no way of unambiguously distinguishing between the interrogation zones corresponding to the shipping functions, and the interrogation zones corresponding to the receiving functions. As a result, when one of the system components can be used for both shipping and receiving, it is difficult to determine whether interrogations performed by that component are associated with the shipping or receiving functions, especially when the component interrogates tagged items located within the overlapping region of the two interrogation zones. Not only may one or more components of the conventional RFID system be used to perform multiple functions, but they may also be associated with more than one physical location within the system environment. This often occurs when RFID system components are mobile. However, as discussed above, in conventional RFID systems, there is no easy way of tying the system components to the physical locations within the system environment, whether those locations are permanent or merely temporary.
It would therefore be desirable to have a system and method of managing the configuration and control of components of an RFID system that maintains specified associations between the system components and actual physical locations within an environment in which the RFID system is deployed. Such a system and method would allow the associations between the system components and the physical locations to be specified in a dynamic fashion based primarily upon how the various components are employed within the system environment. Such a system and method would also allow logical and physical relationships between the system components and the physical locations to be determined in accordance with how the components and locations are associated with one another.
It would also be desirable to have a system and method of visualizing (1) the placement of RFID system components within the RFID system environment with reference to actual physical locations within the environment, (2) the RF coverage areas associated with the various system components disposed at those physical locations, and/or (3) the regions within the system environment in which system components with similar properties are located. Such a system and method would allow properties to be assigned to both the system components and the physical locations, while providing a better understanding of how the components and locations exist within the system environment, leading to more cooperative information gathering among the various system components and more meaningful decision making based upon the acquired information.